1. Field of the Invention
This invention relates to closures for sealing material-dispensing conduits such as tubing, nozzles, hoses and the like, and more particularly to a multi-purpose plug for removably resealing, to prevent leakage and hardening, the end of a straw-like plastic tube such as is commonly used to dispense sealant from a can, the tapered nozzle of a cartridge or squeeze tube such as is typically used to dispense adhesive sealant or caulking, or the circular aperture of a squeeze tube such as is used for glue or pipe thread compound.
2. Description of the Related Art
Foam sealants, which expand to take the shape of cracks and voids and then cure to provide a hardened insulating material, typically are sold in pressurized cans having a trigger or similar dispensing mechanism to open an aperture therein releasing the polyurethane- or latex-based foam. Frequently, a length of straw-like plastic tubing, i.e., a tube having a small, circular cross-section bore, is packaged with a can. Inserted into the mechanism, the tube provides a means of aiming and dispensing the sealant. Typically, the material inside the can is liquid, becoming foam as it exits the aperture. Once the can is opened and used, residual material inside the tube begins to harden so that further dispensing eventually becomes impossible, in as little as two hours if the material is polyurethane-based. Usually a replacement tube is not at hand, so the can cannot be used again unless considerable time and effort are spent in removing the clog. Frequently a user will dispose of a can which still contains much material, rather than face the prospect of cleaning out the tube after each use. A removable plug which reliably seals the tubing end would permit storing an opened can for at least three to four weeks and possibly for several months, depending on the material, and using it repetitively until all its material is depleted.
Containers used for packaging adhesive sealant, glue, caulking, pipe thread compound and the like come in several forms. In the xe2x80x9cscrew-on nozzlexe2x80x9d variety a cartridge or squeeze tube comes with a cap and a separate attachable-detachable nozzle. After completing a job, a user is supposed to remove and ream out the nozzle bore, then recap the tube. Often, the user forgets or fails to adequately clean the nozzle so residual material in the bore hardens, and the container is found to be unusable the next time it is needed so it is discarded. In the xe2x80x9cfixed nozzlexe2x80x9d variety a cartridge or squeeze tube comes with an attached molded nozzle. Typically a squeeze tube nozzle is covered with an interference-fit cap to be used after the nozzle has been cut. Often the nozzle is cut to so large a diameter that the cap no longer fits properly or at all, or the cap is lost and a replacement cap is unavailable. If either variety is not properly sealed, material therein hardens leaving the cartridge or tube unusable. In the xe2x80x9ccap onlyxe2x80x9d variety a squeeze tube typically has a generally circular outlet initially sealed by a membrane covered by a screw-on cap. The membrane must be pierced before material can be squeezed out. The tube is resealed by replacing the cap. If the cap is lost, material in the outlet becomes hardened and the tube becomes unusable.
My U.S. Pat. No. 6,481,597 B1 (xe2x80x9c""597xe2x80x9d), entitled xe2x80x9cPlug Assembly For Removably Resealing A Caulking Tube Nozzle And Method Of Use,xe2x80x9d which is incorporated herein in its entirety by this reference, discloses a plug having a conically tapering lower portion with contiguous scoring edges each having a leading and a trailing surface which form a sharp circumferential point. The edges have a barb-like shape which presents little resistance going in but is highly resistant to being pulled directly out, rather than being screwed out. By rotationally inserting the plug into the aperture of a caulking or adhesive tube nozzle, at least one point scores the nozzle interior surface to form grooves. The scoring edges are configured so that a small annular air space exists between each pair of contiguous edges and the interior surface after the points penetrate the surface. Meshing of points and grooves in combination with residual caulking material in the nozzle bore, extruded into the air spaces, create an air-tight seal. The nozzle, reopened by unscrewing the plug, can be repetitively resealed because the scoring edges always track within the preformed grooves.
The ""597 plug is specialized to sealing caulking tube nozzles and the like because it requires the presence of residual hardenable material in the nozzle bore. What is needed is a multi-purpose plug able to seal a variety of material-dispensing plastic conduits including straw-type tubing, screw-on nozzles, fixed nozzles, and pierced-membrane outlets, without requiring cooperation with residual material.
In view of the limitations of the ""597 plug, it is an object of the present invention to provide a plug capable of removably resealing the outlet aperture of a dispensing conduit made of a soft plastic which is attached or connected to a variety of pressurized cans, cartridges, squeeze tubes and similar containers containing, respectively, a variety of high, medium or low viscosity materials.
Another object of the invention is to provide a plug that is simple to use and inexpensive to buy, even in quantity.
Other objects of the invention will become evident when the following description is considered with the accompanying drawing figures. In the figures and description, numerals indicate the various features of the invention, like numerals referring to like features throughout both the drawings and description.
These and other objects are achieved by the present invention which in one aspect provides a plug for removably resealing an aperture in a dispensing conduit made of a deformable soft plastic and having an annular end segment proximate to the aperture. The plug includes a conically tapering lower portion having a multiplicity of successively contiguous circumferential scoring edges terminating in a leading scoring edge proximate to a distal end. Each distally successive scoring edge is slightly smaller in circumference. Each scoring edge is canted rearwardly at a first acute angle to a common longitudinal axis, and has a leading edge surface making a second acute angle with respect to an axis orthogonal to the longitudinal axis and a trailing edge surface making a third acute angle with respect to the orthogonal axis. The leading and trailing edge surfaces form a sharp point, and each adjacent pair of scoring edges are separated by a distally tapering circumferential surface. Each point has a common height with respect to the two distally tapering surfaces bounding the point, respectively, proximally and distally. The distal end of the plug lower portion is sized to enable penetration of the conduit aperture by at least the leading scoring edge, thereby contacting and scoring at least one groove in the end segment to a depth equal to the point height.
In another aspect the invention provides a plug for removably resealing an aperture in a dispensing conduit made of a deformable soft plastic and having an annular end segment proximate to the aperture. The plug includes an upper portion having a planar top surface orthogonal to a plurality of convexly arcuate knurls, with each pair of neighboring knurls separated by a concavely arcuate depression. The plug further includes a circumferential skirt having a polygonal plurality of planar edge segments and attached to the plug upper portion. The plug further includes a conically tapering lower portion, attached to the skirt, having a multiplicity of successively contiguous circumferential scoring edges terminating in a leading scoring edge proximate to a distal end with a rounded tip. Each distally successive scoring edge is slightly smaller in circumference. Each scoring edge is canted rearwardly at a first acute angle to a common longitudinal axis, and has a leading edge surface making a second acute angle with respect to an axis orthogonal to the longitudinal axis and a trailing edge surface making a third acute angle with respect to the orthogonal axis. The leading and trailing edge surfaces forming a sharp point, and each adjacent pair of scoring edges are separated by a distally tapering circumferential surface. Each point has a common height with respect to the two distally tapering surfaces bounding the point, respectively, proximally and distally. The distal end of the plug lower portion is sized to enable penetration of the aperture by at least the leading scoring edge, thereby contacting and scoring at least one groove in the end segment to a depth equal to the point height.
In yet another aspect the invention provides a method for removably resealing an aperture in a dispensing conduit made of a deformable soft plastic and having an annular end segment proximate to the aperture. The method includes the step of gripping a handle-like upper portion of a plug which is rigidly attached to a conically tapering lower portion having a multiplicity of successively contiguous circumferential scoring edges terminating in a leading scoring edge proximate to a distal end sized to enable penetration of the aperture by at least the leading scoring edge. Each distally successive scoring edge is slightly smaller in circumference, and each scoring edge is canted rearwardly at a first acute angle to a common longitudinal axis and has a leading edge surface making a second acute angle with respect to an axis orthogonal to the longitudinal axis and a trailing edge surface making a third acute angle with respect to the orthogonal axis. The leading and trailing edge surfaces form a sharp point, and each adjacent pair of scoring edges are separated by a distally tapering circumferential surface. Each point has a common height with respect to the two distally tapering surfaces bounding the point, respectively, proximally and distally. The method further includes the steps of: penetrating the aperture with at least the leading scoring edge, thereby contacting and scoring at least one groove in the end segment to a depth equal to the point height; and screwing in the plug so as to penetrate further into the conduit bore, thereby scoring additional grooves in the end segment, to a depth equal to the point height, as additional scoring edge points contact the end segment.